Interactive media environments are typically resource constrained in terms of available processing power, memory and other resources that are available to applications running in the environment. One common example of interactive media is video encoded on DVD (digital versatile disc) where users can interact with graphical menus or other controls to navigate to specific video content or invoke special features that are authored into the DVD.
In a typical interactive media environment, visual elements such as graphics and menus are given a “Z order” that provides a visual order for the elements on a display screen. The Z order controls how visual elements appear to stack on top of one another along an imaginary z-axis which extends outwardly from the display screen. Visual elements with a lower Z order appear to be at the bottom of display (and farther away from a viewer) while visual elements with a higher Z order appear to be on top of the lower Z ordered elements (and thus closer to the viewer).
When multiple applications used to generate visual elements are running in an interactive media environment, input events must be distributed to the applications. Input events must be handled in a resource-efficient manner. In addition, applications must be enabled to generate graphical output responsively to input from the environment to dynamically create a rich interactive experience for users.